1. Field of the Invention
The present invention relates to a technique for capturing images of one or more objects to be displayed in three dimensions, and a technique for displaying the objects of the captured images in three dimensions. More specifically, the present invention is directed to an imaging device and a display device which both use a lens array composed of multiple focusing members arranged on the same level.
2. Description of the Related Art
To produce three-dimensional (3D) images at a specific view point, the known integral photography (IP) technique is being employed (see Japanese Unexamined Patent Application Publication 8-289329). In this IP technique, one or more objects are focused by multiple lenses (lens array) or pin holes arranged on the same level, and the image of the focused objects is then captured. Following this, the captured image is displayed. Finally, a person (viewer) can see the displayed image at a specific position through the lens array. In this way, it is possible for 3D images to be presented.
A detailed description will be given below, of the IP technique using a convex lens array composed of multiple convex lenses, with reference to FIGS. 20A to 23B. FIGS. 19A and 19B show a general mode in which objects are captured according to the conventional IP technique. More specifically, FIG. 20A shows a conventional imaging device according to the IP technique, and FIG. 20B shows a schematic image captured by the imaging device. FIG. 21 shows the characteristics of the lateral optical magnification of images focused by the convex lenses of the imaging device. FIG. 22 shows a schematic conversion manner of an image captured with the IP technique. FIGS. 23A and 23B show a mode in which an image of objects is displayed in three dimensions with the IP technique. More specifically, FIG. 23A shows the schematic configuration of a display device according to the IP technique and a mode in which an image of objects is displayed in three dimensions by the display device. Furthermore, FIG. 23B shows the image presented on a display of the display device.
Firstly, referring to FIG. 20A, an imaging device 110 according to the IP technique will be described. In this figure, objects are two point light sources 115a and 115b, and convex lenses constituting a convex lens array 112 are three convex lenses 111b, 111c and 111d. In addition, these lenses are all arranged adjacent to one another.
The imaging device 110 includes the convex lens array 112 and a camera 113. Furthermore, the convex lens array 112 is composed of multiple convex lenses 111b, 111c and 111d arranged on the same level. This lens array 112 focuses light from objects (point light sources 115a and 115b) on the camera 113. The camera 113 captures images of the objects. To be concrete, the point light sources 115a and 115b emit light in various directions. Part of the light passes through the convex lens 111b, 111c and 111d, and this light then enters an objective lens 114. This objective lens 114 converges the entered light on an imaging element (not shown) of the camera 113, so that an image of the point light sources 115a and 115b appears thereon. Finally, the image of the point light sources 115a and 115b is captured by the camera 113. In this function, it should be noted that the captured image is inverted in orientation.
The characteristics of lateral optical magnification “m” of the object focused by each convex lens are revealed in FIG. 21. In this figure, “L11” stands for a distance between the object and each convex lens, and “f” stands for the focal length of each convex lens. As is clearly found from this figure, if “L11” is less than “−f”, then “m” is of a negative value, whereby the captured object is inverted. Otherwise, if “L11” is more than “−f”, then “m” is of a positive value so that the captured object is positionally correct, that is, non-inverted. Accordingly, when the image of the point light sources 115a and 115b which is away from each convex lens by more than its focal length is captured, the captured image ends up being inverted.
As shown in FIG. 20B, an image 121 captured by the camera 113 is inverted. Naturally, the image appearing on each convex lens is also inverted.
Therefore, the image 121 needs to undergo a computing process in order to convert the inverted objects, which have been captured by the imaging device 110, into non-inverted objects, that is, positionally correct objects.
Next, with reference to FIG. 22, a description will be given below, of a method for converting the inverted image 121 of FIG. 20A into a non-inverted image. This figure shows individual images of the convex lenses 111b, 111c and 111d. 
As shown in FIG. 22, the image 121 having been captured by the imaging device 110 is first divided into three images 122b, 122c and 122d. These three images correspond to the individual convex lens 111b, 111c and 111d. Following this, each of the images 122b, 122c and 122d is rotated by 180 degrees, and the rotated images 123b, 123c and 123d are then combined into a single image 124. Thus, the non-inverted image (IP image) is created.
Secondly, subsequent to the imaging device, a display device 130 according to the IP technique will be described with reference to FIGS. 23A and 23B. The display device 130 includes a display 131 and a convex lens array 133. The display 131 has a function of presenting an image 124 (IF image) thereon. The convex lens array 133 is composed of convex lenses 132b, 132c, 132d, etc. arrange on the same level, facing the display 131. Light emitted from objects 134a and 134b passes through the display 131, and then, through the convex lenses 132b, 132c and 132d. In this case, when a person (viewer) sees an image on the display 131 through the convex lens 132, the objects 134a and 134b of the image which the person sees are non-inverted. These objects 134a and 134b have the same orientation as that of the point light sources 115a and 115b of FIG. 20A. This makes it possible to display the 3D image of non-inverted, that is, positionally correct objects without the use of any special glasses or any other similar tools.
In addition to the above imaging device, another imaging device has been proposed, using an inverting optical system instead of the computing process (see Three-dimensional Imaging Techniques, T. Okoshi, Academic, New York, 1971). In this imaging device, one or more objects that have been inverted by a convex lens array are re-inverted by the inverting optical system. Consequently, the IP image of non-inverted objects can be acquired. This inverting optical system is constituted by multiple prisms and a large-diameter lens.
Moreover, an additional imaging device has been proposed, using a graded-index lens such as an optical fiber instead of the convex lenses of FIG. 20A (see Japanese Unexamined Patent Application Publication 10-150675). This imaging device enables the non-inverted IP images to be captured without performing the computing process, because the focused images are not inverted.
However, each of the above imaging devices may suffer from the following disadvantages.
The imaging device described in JP8-289329 requires the installation of a large-scale electric circuit for performing the computing process.
The imaging device described in “Three-dimensional Imaging Techniques” needs many optical components such as prisms. In addition, the imaging device described in JP10-150675 is required to have graded-index lenses. These optical components are more difficult to arrange on the same level than typical convex or concave lenses.
Taking the above disadvantages into account, the present invention has been conceived. An object of the present invention is to provide a simple imaging device and display device without any need of an image conversion. Therefore, an additional object of the present invention is to provide imaging and display devices capable of being both manufactured at low costs.